lldb_symbols.py

#!/usr/bin/env python
# Any copyright is dedicated to the Public Domain.
# http://creativecommons.org/publicdomain/zero/1.0/

import lldb
import gzip
import io
import itertools
import os
import shutil
import tarfile

try:
    from urllib.request import urlopen
    from urllib.parse import urljoin, quote
except ImportError:
    from urllib2 import urlopen
    from urllib import quote
    from urlparse import urljoin

SYMBOL_SERVER_URL = 'https://symbols.mozilla.org/'
cache_dir = os.path.join(os.environ['HOME'], 'Library', 'SymbolCache', 'dsyms')
uuid_dir = os.path.join(cache_dir, 'uuids')


def munge_build_id(build_id):
    '''
    Breakpad stuffs the build id into a GUID struct so the bytes are
    flipped from the standard presentation.
    '''
    b = list(map(''.join, list(zip(*[iter(build_id.upper())]*2))))
    return ''.join(itertools.chain(reversed(b[:4]), reversed(b[4:6]),
                                   reversed(b[6:8]), b[8:16])) + '0'


def is_moz_binary(filename):
    '''
    Try to determine if a file lives in a Firefox install dir, to save
    HTTP requests for things that aren't going to work.
    '''
    # The linux-gate VDSO doesn't have a real filename.
    if not os.path.isfile(filename):
        return False
    while True:
        filename = os.path.dirname(filename)
        if filename == '/':
            return False
        if os.path.isfile(os.path.join(filename, 'application.ini')):
            return True

def try_fetch_symbols(filename, build_id, destination, is_mac):
    if is_mac:
        debug_file = os.path.join(destination, filename + '.dSYM', 'Contents',
                                  'Resources', 'DWARF', filename)
    else:
        debug_file = os.path.join(destination, build_id[:2], build_id[2:] + '.debug')
    if os.path.exists(debug_file):
        return debug_file
    try:
        d = os.path.dirname(debug_file)
        if not os.path.isdir(d):
            os.makedirs(d)
    except OSError:
        pass
    if is_mac:
        path = os.path.join(filename, build_id + '0',
                            filename + '.dSYM.tar.bz2')
    else:
        path = os.path.join(filename, munge_build_id(build_id),
                            filename + '.dbg.gz')
    url = urljoin(SYMBOL_SERVER_URL, quote(path))
    try:
        u = urlopen(url)
        if u.getcode() != 200:
            return None
        print('Fetching symbols from {0}'.format(url))
        if is_mac:
            with tarfile.open(fileobj=io.BytesIO(u.read()), mode='r:bz2') as t:
                t.extractall(destination)
            return debug_file
        else:
            with open(debug_file, 'wb') as f, gzip.GzipFile(fileobj=io.BytesIO(u.read()), mode='r') as z:
                shutil.copyfileobj(z, f)
                return debug_file
    except Exception as e:
        print 'Error: %s' % e
        return None


def fetch_symbols(debugger, command, exe_ctx, result, internal_dict):
    '''Attempt to fetch symbols from Mozilla's symbol server'''
    target = exe_ctx.target
    is_mac = target.triple.endswith('-apple-macosx')
    for m in target.module_iter():
        path = m.file.fullpath
        if m.file == m.GetSymbolFileSpec() and is_moz_binary(path):
            uuid = m.uuid.hex
            debug_file = try_fetch_symbols(os.path.basename(path), uuid,
                                           cache_dir, is_mac)
            if debug_file is not None:
                print 'Downloaded: %s' % debug_file
                lldb.debugger.HandleCommand('target symbols add ' + debug_file)


def __lldb_init_module(debugger, internal_dict):
    print 'Loaded lldb-symbols. target: %s' % debugger.GetSelectedTarget()
    try:
        if not os.path.isdir(cache_dir):
            os.makedirs(cache_dir)
    except OSError:
        pass
    lldb.debugger.HandleCommand('command script add -f lldb_symbols.fetch_symbols fetch-symbols')